KR20150024292A - Bottom-up fill in damascene features - Google Patents

Abstract

Embodiments of the present invention relate to a method and an apparatus for filling features with copper by a bottom-up filling mechanism without using organic plating additives. In some cases, filling is directly carried out on a semiprecious metal layer without depositioning a copper seed layer. In other cases, filling is carried out on the copper seed layer. Factors such as polarization of an electrolyte, use of a complexing agent, electrolyte pH, and waveform used in depositioning the temperature of the electrolyte and a material can contribute to the promotion of the bottom-up filling.

Description

BOTTOM-UP FILL IN DAMASCENE FEATURES in damascene features.

In damascene processing, copper is deposited into features on partially fabricated semiconductor substrates. Conventional copper deposition typically takes place in two steps. First, the copper seed layer is deposited on the substrate using physical vapor deposition (PVD). The copper is then electroplated onto the seed layer to fill the features. As the dimension of the damascene interconnects decreases over time, it becomes increasingly difficult to obtain uniform copper coverage over all surfaces when depositing the seed layer through PVD. Uneven seed layer coverage is problematic because thin copper seed regions are particularly susceptible to oxidation and dissolution in the electrolyte during the initial stages of the electroplating process. In other words, a thinner seed zone (e.g., on the sidewalls of the feature) tends to dissolve in the electrolyte resulting in a discontinuous metal seed layer. When electroplating occurs on this discontinuous seed layer, the plating results are non-uniform and defects may be introduced.

Certain techniques (e.g., immersion in high voltage initial plating conditions, seed pre-treatment, etc.) may be used to reduce seed dissolution. However, even if these techniques are used perfectly, dissolution of a certain seed amount is expected. There is therefore a need for a method of depositing copper in semiconductor features that require deposition of a copper seed layer.

The developed technique does not use PVD to deposit the copper seed by electroplating the copper seed layer directly onto a semi-noble surface such as a ruthenium layer. However, the process used to electroplating the seed layer and subsequently the process used to fill the features requires substantially different electrolytes, and thus the copper electroplating must occur over two separate processes.

Electrolytes used in electrodepositing copper on the seed layer in damascene interconnects typically include copper salts, acids, halide ions, accelerators, inhibitors, and leveling agents. The copper salt is the copper source to deposit. The acid is generally used to control the conductivity of the plating bath. The halide ions support the adsorption of certain organic additives (accelerators, inhibitors and / or leveling agents) onto the substrate surface and serve to promote the conventional bottom-up charging mechanism as described below.

In the conventional electroplating of copper, the organic additives are important to achieve the desired metallurgical properties, film uniformity, defect control and filling performance. However, the concentration of organic additives varies with time and requires careful care to trace the electrolyte composition to ensure proper plating results. The concentrations of the additives are very low in many cases and it is difficult to accurately trace the electrolyte concentration within the appropriate tolerances. Because of this difficulty, certain portions of the substrate may be plated in baths that do not have the proper balance of additives and may not be suitable for subsequent use. There is therefore a need for a method of electroplating copper into semiconductor features that does not employ conventional organic additives such as accelerators, inhibitors, or leveling agents.

Certain embodiments herein relate to methods and apparatus for performing bottom-up filling into a feature on a substrate. In one aspect of embodiments herein, a method is provided for performing a single step electrofill process to fill features on a partially fabricated integrated circuit. The method includes the steps of: (a) receiving a substrate having a semi-noble metal layer and a plurality of features exposed on the substrate; (b) contacting the substrate with an electrolyte, wherein the electrolyte comprises: (i) about 1 to 100 mM copper cations; And (ii) a complexing agent that forms a complex with the copper cations, wherein the electrolyte is substantially free of inhibitors, accelerators, and a planarizing agent; And (c) a bottom-up filling mechanism at a substrate potential for electrodeposition of about 0.03 to 0.33 V relative to an NHE (normal hydrogen eletrode) reference electrode while in contact with the electrolyte, Lt; RTI ID = 0.0 > electroplating < / RTI >

In various embodiments, the inhibitors, accelerators or leveling agents may not contribute substantially to the bottom-up filling mechanism. Bottom-up filling may be performed directly on the semi-precious metal layer, without forming a seed layer. A variety of different waveforms may be used. In some cases, electroplating the copper in (c) comprises alternating between a first level of depositing copper on the substrate and a second level of etching copper from the previously electroplated copper on the substrate And applying pulsed modulated waveforms. The second level of current etching copper may have an absolute value of less than about 0.1 mA for a 300 mm diameter wafer. In certain embodiments, pulses of current alternate between about 100 and 1000 Hz between a first current level and a second current level. In these or other cases, the electroplating surface of the substrate may experience a current density of about 0.004 to 0.4 mA / cm < ^{2 &} gt ;.

A number of different complexing agents may be used. In some embodiments, the complexing agent is selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid, and glutamic acid. In certain cases, the complexing agent is ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetic acid (NTA). The electrolyte may be at or near room temperature. In one embodiment, the electrolyte is maintained at a temperature of about 20 to 80 캜, such as about 50 to 70 캜. The pH of the electrolyte is about 1 to 5, and in some cases it can be about 1.5 to 3.5. The dissolved oxygen content of the electrolyte may be about 2 ppm or less.

The methods herein may be used for plating on a variety of different metals. In some cases, the semi-precious metal layer comprises a material selected from the group consisting of ruthenium, tungsten, cobalt, osmium, platinum, palladium, aluminum, gold, silver, iridium and rhodium. In certain cases, the semi-precious metal layer is ruthenium. In some embodiments, at least some of the features on the semiconductor substrate may have an open width of about 100 nm or less. For example, in some cases, the features may have a width of about 20 nm or less.

In another aspect of the disclosed embodiments, a method of depositing copper in a feature on a partially fabricated integrated circuit is provided. The method includes the steps of: (a) receiving a substrate having a plurality of features and a copper seed layer on a substrate; (b) contacting the substrate with an electrolyte, wherein the electrolyte comprises (i) about 1 to 100 mM copper cations, wherein the electrolyte is substantially free of inhibitors, accelerators and planarizing agent, ; And (c) electroplating the copper into the feature by a bottom-up filling mechanism at a potential of about 0.03 to 0.33 V for a normal hydrogen eletrode reference electrode.

In some embodiments, during electroplating, the electrolyte is maintained at a temperature of about 20 to 80 캜, for example, about 20 to 50 캜. The electroplating surface of the substrate may experience a current density of about 0.004 to 0.4 mA / cm < ^{2 &} gt ;. In certain embodiments, the pH of the electrolyte is from about 1 to about 5, such as from about 1.5 to about 3.5. The disclosed methods may be used to fill relatively small features. In some cases, at least some of the features have a width of about 100 nm or less, e.g., about 20 nm or less. In certain embodiments, electroplating copper in (c) comprises applying a galvanostatically controlled current to the substrate.

These and other features will be described below with reference to the accompanying drawings.

Figure 1 is a flow chart of a method of electroplating copper into a feature on a substrate having an exposed precious metal layer.
2 is a flow chart of a method of electroplating copper into a feature on a substrate having an exposed copper seed layer.
Figure 3 illustrates an exemplary multi-station device in accordance with the disclosed embodiments.
Figure 4 is another implementation of a multi-station device in accordance with the disclosed embodiments.
Figure 5 is a graph showing the relative polarization effects of different complexing agents in the electrolyte.
Figure 6 is a graph showing the relative polarization effects of different copper cation concentrations and different pH levels in the electrolyte.
Figure 7 is a graph showing the relative polarization effects of different electrolyte temperatures.
Figures 8a-8c show SEM images of ruthenium seeded trench coupons plated at 0.4 mA (Figure 8a), 0.6 mA (Figure 8b), and 1 mA (Figure 8c).
Figures 9a-9c show SEM images of plated ruthenium seeded trench coupons using modulated waveforms at room temperature (Figure 9a), 50 ° C (Figure 9b), and 70 ° C (Figure 9c).
Figures 10a and 10b show SEM images of ruthenium seeded trench coupons plated in electrolytes containing NTA (Figure 10a) and glutamic acid as complexing agents.
Figures 11a-11c and 12a-12c illustrate cross-sectional SEM images (Figures 11a-11c) and top-down SEM images of copper seeded trench coupons plated at different temperatures 12C). ≪ / RTI >
Figure 13 shows a TEM image of a copper-seeded trench coupon plated in an electrolyte free of complexing agent.

In this specification, the terms "semiconductor wafer", "wafer", "substrate", "wafer substrate" and "partially fabricated integrated circuit" are used interchangeably. A person skilled in the art can refer to a "partially fabricated integrated circuit" as a silicon wafer during any of a plurality of integrated circuit fabrication stages thereon. The wafer or substrate used in the semiconductor device industry typically has a diameter of 200 mm, 300 mm or 450 mm. The terms "electrolyte "," plating bath ", "bath" and "plating solution" are also used interchangeably. The following detailed description assumes that the present invention is implemented on a wafer. However, the present invention is not limited thereto. The workpiece may have various sizes, shapes and materials. In addition to semiconductor wafers, other workpieces that may utilize the present invention include various objects such as printed circuit boards and the like.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments provided. The disclosed embodiments may be practiced without all or any of these specific details. In other instances, well-known process operations have not been described in detail in order not to unnecessarily obscure the disclosed embodiments. While the disclosed embodiments are described in connection with specific embodiments, it should be understood that they should not be construed as limiting the disclosed embodiments.

As noted above, conventional copper deposition processes typically employ organic additives such as inhibitors, accelerators, and leveling agents to achieve bottom-up filling. Although the embodiments herein do not require the use of these additives and may benefit from their absence, the additives will be discussed below for comparison with the disclosed embodiments.

Inhibitors

Without being bound by any action mechanism or theory, it is believed that inhibitors, when present together with the surface chemisorbable (such as chloride or bromide) (especially with or without other bath additives) It is considered to be a surface-kinetic polarizing compound that greatly increases the voltage drop. The halide can act as a chemisorbed-bridge between the inhibitor molecules and the wafer surface. The inhibitor (1) increases the local polarization of the substrate surface in regions where the inhibitor is present compared to the regions where no inhibitor is present, and (2) increases the polarization of the substrate surface as a whole. Increased polarization (local and / or global polarization) corresponds to increased resistance / impedance, thereby corresponding to slower plating at certain applied potentials.

Although the inhibitors are adsorbed onto the substrate surface, it is believed that the inhibitors are not included in the deposited film and slowly deteriorate over time. Compounds that do not act predominantly by adsorption onto the substrate surface are not considered inhibitors. In some cases, inhibitors are relatively large molecules, and in many cases the inhibitors are naturally polymeric (e.g., polyethylene oxide, polypropylene oxide, polyethylene glycol, poly Propylene glycol, etc.). Other examples of inhibitors are polyethylene oxide and block polymers of polypropylene oxide, polyethylene oxide and polypropylene oxide having S-containing and / or N-containing functional groups. And the like. Inhibitors may have linear chain structures or branch structures. It is common for inhibitor molecules with various molecular weights to coexist in a commercial inhibitor solution. Due to the large size of the inhibitor in part, the diffusion of these compounds into the recessed features may be relatively slow.

Accelerators

Without being bound by any mechanism or theory of action, the accelerators tend to locally reduce the polarization effect associated with the presence of inhibitors (either alone or in combination with other bath additives), thereby locally increasing the electrodeposition rate . The reduced polarization effect is most pronounced in the areas in which the adsorbed accelerator is most concentrated (i.e., the polarization is reduced as a function of the local surface concentration of the adsorbed accelerator). Exemplary accelerators include, but are not limited to, dimercaptopropane sulfonic acid (DSA), dimercaptoethane sulfonic acid, mercaptopropane sulfonic acid (MSA), mercaptoethane sulfonic acid, SPS bis- (3-sulfopropyl) disulfide, and derivatives thereof. The accelerator is strongly adsorbed on the substrate surface due to the plating reactions and is generally surface-fixed laterally, but the accelerator is generally not introduced into the film. As a result, the accelerator remains on the surface when the metal is deposited. As the recess is filled, the local accelerator concentration increases on the surface in the recess. Accelerators are small molecules compared to inhibitors and tend to exhibit rapid diffusion into the recessed features. Compounds that do not act predominantly by adsorption onto the substrate surface are not considered accelerators.

Flatteners

Without being bound by any mechanism or theory of action, it is believed that the planarizing agents (either alone or together with other bath additives) act as inhibitors to offset the depolarizing effects associated with the accelerators, particularly in the sidewalls of the field regions and features. The planarizing agent locally increases the polarization / surface resistance of the substrate, thereby slowing the local electrical deposition reaction in the areas where the planarizing agent is adsorbed. The local concentration of the leveling agent is determined to some extent by mass transport. Thus, the leveling agent acts mainly on surface structures having geometries that protrude away from the surface. This action "planarizes" the surface of the electrically-deposited layer. In many cases, the leveling agent is reacted or consumed at the substrate surface at a rate that is at or near a diffusion limited rate, and thus a continuous supply of the leveling agent is sometimes advantageous in maintaining uniform plating conditions over time.

Planarizing compounds are generally classified as various planarizing agents based on their electrochemical function and effect and do not require a particular chemical structure or formulation. However, the leveling agent sometimes contains one or more nitrogen, amine, imide or amidazole and may also contain sulfur functional groups. Compounds that do not act predominantly by adsorption on the substrate surface are not considered as planarizing agents. Specific planarizing agents include one or more 5 and 6 member rings and / or conjugated organic compound derivatives. The nitrogen group may form part of the ring structure. In the amine-containing leveling agents, the amines may be primary alkyl amines, secondary alkyl amines or tertiary alkyl amines. In addition, the amine may be an arylamine or a heterocyclic amine. Exemplary amines include, but are not limited to, dialkylamines, trialkylamines, arylalkylamines, triazoles, imidazole, triazole, tetra The present invention relates to a process for the preparation of benzimidazole derivatives of the formula I wherein R is selected from the group consisting of tetrazole, benzimidazole, benzotriazole, piperidine, morpholines, piperazine, pyridine, oxazole, Include benzoxazole, pyrimidine, quinoline, and isoquinoline. Imidazole and pyridine may be particularly useful. The planarizing compounds may also include ethoxide groups. For example, the leveling agent may comprise a common backbone similar to that found in polyethylene glycol or polyethylene oxide and fragments of functionally inserted amines across the chain (see, for example, Janus Green B). Examples include, but are not limited to, epihalohydrins, such as epichlorohydrin and epibromohydrin, and polyepoxide compounds. Polyepoxide compounds having two or more epoxide moieties bonded together by an ether-containing linkage may be particularly useful. Some of the planarizing compounds are polymeric, while others are not. Exemplary polymeric planarizing compounds include, but are not limited to, polyethylenimine, polyamidoamines, and reaction products of amines and various oxygen epoxides or sulfides. One example of a non-polymeric leveling agent is 6-mercapto-hexanol. Another exemplary leveling agent is PVP (polyvinylpyrrolidone).

Bottom-up filling promoted by organic additives

In the bottom-up filling mechanism, the recessed surface on the plating surface tends to be plated with metal from the bottom to top of the feature and from the sidewall of the feature to the center of the feature on the inside. In order to achieve uniform filling and avoid introducing voids in the feature, it is important to control the deposition rate in the feature and in the field area. In typical applications, the three types of additives described above are advantageous to achieve bottom-up filling, and each additive operates to selectively increase or decrease polarization at the substrate surface.

After the substrate is immersed in the electrolyte, the inhibitor is adsorbed onto the surface of the substrate, particularly in the exposed areas such as the field areas. In the initial plating stages, there is a substantial difference in inhibitor concentration between the top and bottom of the recessed features. This difference is due to the relatively large size of the inhibitor molecule and its corresponding slow transfer characteristics. Over this same initial plating time, it is believed that the accelerator accumulates at a low and substantially uniform concentration over the entire plating surface including the bottom and sidewalls of the feature. Since the accelerator diffuses into the feature faster than the inhibitor, the initial ratio of the accelerator: inhibitor in the feature (particularly at the bottom of the feature) is relatively high. This relatively high initial accelerator: inhibitor ratio in the features promotes rapid plating from the bottom of the feature to the top and from the sidewalls to the inside. On the other hand, the initial plating rate in the field region is relatively low due to the low accelerator: inhibitor ratio. Thus, in the initial plating stages, plating occurs relatively slowly within the field area and occurs relatively quickly within the feature.

As plating progresses, the features are filled with metal and the surface area within the features is reduced. As the surface area is reduced and the accelerator remains substantially on the surface, the local surface concentration of the accelerator in the feature increases as the plating proceeds. This increased accelerator concentration in the features helps to maintain a useful plating rate difference in the bottom-up fill.

In subsequent stages of plating, particularly as an overburden is deposited, the accelerator accumulates undesirably in certain areas (e.g., on filled features), thereby resulting in localized Plating occurs. Planarizing agents are typically used to offset these effects. The surface concentration of the planarizing agent is highest in the exposed areas of the surface where convection is most active (i.e., not in the recessed features). The planarizing agent replaces the accelerator and increases the local polarization and reduces the local plating rate in areas of the surface, otherwise these areas can be plated at higher rates in other areas of the deposition. In other words, the leveling agent has a tendency to at least partially reduce or eliminate the influence of the accelerator component in the exposed areas of the surface, especially in the protruding structures. In typical applications, if there is no planarizing agent, the feature will overfill and have a tendency to produce a bump. Thus, in subsequent stages of bottom-up fill plating, the flattening agent is advantageous to create a relatively flat deposition layer.

The use of inhibitors, accelerators, and leveling agents together results in a relatively flat deposited surface while allowing the feature to fill inward from the sidewall upward at the bottom without void formation. The exact conformation / composition of the additive compounds is kept as trade secret by additive suppliers and therefore information on the exact nature of these compounds is not available to the public.

Plating without organic additives

One aspect of the disclosed embodiments is a method of electroplating copper into features on a semiconductor substrate having an exposed semi-noble metal liner. In this embodiment, the copper is electroplated directly onto the semiprecious metal liner, rather than over the copper seed layer. In this embodiment, the electrolyte is substantially free of organic additives such as inhibitors, accelerators, and leveling agents, when the electrolyte may include a complexing agent that complexes with copper in solution. In the presence of a small amount of organic additives, the organic additives may not contribute substantially to the bottom-up filling mechanism. In other words, even when there are no organic additives, when plating under the same different plating conditions, bottom-up filling will occur. Another aspect of the disclosed embodiments is a method of electroplating copper into features on a semiconductor substrate having an exposed copper seed layer. As in previous embodiments, the method may be performed using an electrolyte that is substantially free of organic additives such as inhibitors, accelerators, and leveling agents. Despite the absence of these organic additives, the disclosed method achieves a bottom-up filling mechanism to fill the features.

Methods

Plating on the precious metal layer

In one embodiment, copper is electroplated onto the exposed precious metal liner layer. The semi-precious metal liner layer may be ruthenium, cobalt, tungsten, osmium, platinum, palladium, aluminum, gold, silver, iridium, rhodium or combinations thereof. A substrate having an exposed precious metal layer is provided in the electroplating cell and is immersed in an electrolyte having certain properties as described below. Current is applied to the substrate to promote nucleation followed by Volmer-Weber growth, thereby forming three-dimensional copper islands. Copper islands continue to grow until they are incorporated into a continuous copper film. The applied current depends on the composition of the electrolyte but is generally controlled to provide a voltage of about 0 to 4 V for NHE or about 0.03 to 0.33 V for NHE.

The electrolyte may be designed to assist in promoting high nucleation density. One way to promote high nucleation density is to use conditions that yield relatively highly polarized electrolytes. Increased electrolyte polarization can be achieved by using certain complexing agents such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid, and glutamic acid. These complexing agents form complexes with copper ions dissolved in the electrolyte. Complexing agents bind to copper ions and form soluble complexes, for example, by electrostatic interactions. In various instances, the complexing agents are shaped to partially enclose the complicated copper ions and partially shield the copper ions. The complexing agents are not appreciably adsorbed onto the surface of the substrate, rather than to the extent of conventional plating additives, such as at least inhibitors, accelerators and planarizing agents. Thus, the complexing agents used herein are not inhibitor compounds (or accelerators or planarizing agents). The polarization effects of the complexing agents as described above are exemplified below in the experimental part.

Complexing agents promote high nucleation density. (Since the complexing agents act primarily by forming a complex with copper in solution rather than by adsorption onto the substrate surface), the complexing agents may increase the overpotential of the copper electrodeposition Which is similar to an inhibitor. In some embodiments, the concentration of complexing agents is from about 1 to 100 mM, such as from about 1 to 20 mM, or from about 5 to 10 mM. The concentration of complexing agents may be substantially similar (within about 30 percent) to the concentration of copper cations when measured in molar concentrations. In some instances, these concentrations may be substantially equimolar (e.g., within about 10 percent or within about 5 percent). In certain instances, the complexing agent concentration and the copper cation concentration are exactly equimolar. This equilibrium of complexing agent concentration and copper cation concentration may be advantageous because copper and complexing agent together form a complex at a ratio of 1: 1. In other cases, this concentration may change more significantly. In some embodiments, the complexing agent concentration may be higher than the copper cation concentration. Having a stoichiometric excess of the complexing agent is advantageous in certain embodiments because it allows the bar to yield a greater proportion of complexed copper cations and thereby achieving a high nucleation density on the surface of the semi- It is possible.

In some embodiments, complexing agents may be omitted. When plating on the precious metal layer without a complexing agent, a modulated waveform may be used to assist in promoting the bottom-up plating. The modulated waveform is further described below.

Low copper concentration contributes to the relatively high polarization of the electrolyte. In some embodiments, the copper cation concentration is about 1 to 100 mM, for example, about 1 to 20 mM, or about 5 to 10 mM. The influence of different copper concentrations on solution polarization is further described below in the experimental part.

Another factor affecting electrolyte polarization is pH. In general, electrolytes having a high pH are more polarized. In certain embodiments, the pH of the electrolyte is from about 1 to about 5, such as from about 1.5 to about 3.5. The different electrolyte pH effects are further described below in the experimental part.

The polarization of the electrolyte is also influenced by the electrolyte temperature. In general, low temperatures result in high electrolyte polarization. However, lower temperatures also result in lower deposition rates and more conformal films. In a bottom-up filling situation, conformal membranes are undesirable because conformal membranes can lead to introducing seams / voids inside the features. As such, the increased polarization benefits at low temperatures must be balanced against the benefits of higher temperature and higher deposition rates and fewer conformal films. In some embodiments, the deposition occurs at a temperature of about 20 to 80 캜, such as about 50 to 70 캜. Typical bottom-up filling processes typically occur at about 20 to 25 占 폚. One advantage of the disclosed embodiments is that, if a fill occurs at an elevated temperature, the deposition rate can be higher than in typical processes that occur at substantially lower temperatures.

The waveform applied to drive the electrical deposition also affects the filling mechanism. In some embodiments, the DC current is used (e.g., with galvanostatic or galvano dynamic control). In other embodiments, a modulated waveform is used (e.g., the current alternates between the deposition current and the etching current). The use of modulated waveforms results in a less conformal membrane, which is advantageous in a bottom-up filling situation.

As is known to those skilled in the art, the peak current (upper current limit) used for deposition is affected by the availability of copper at the substrate-electrolyte interface. When the current rises above an acceptable level, the electrolyte experiences copper depletion, which results in poor deposition results. In other words, the amount of copper at the interface may be insufficient to maintain the reduction reaction at the appropriate current level. Instead, a parasitic reaction may occur to maintain the current delivered to the substrate. For example, the electrolyte itself decomposes at the plating interface and begins to produce gas, which results in non-uniform plating, and in some cases may result in nodular growth formation on the substrate. Care should be taken to ensure that the peak current during etching is typically limited only by hardware constraints, but not so high that the current does not remove all of the previously deposited metal.

In some embodiments, the current level used to deposit the material is about 0.001 to 1.5 A, for example about 0.05 to 1.4 A or about 0.05 to 1 A (based on a 300 mm wafer). In these or other embodiments, the absolute value of the current level used to etch the material is about 0.035 to 0.25 A, for example about 0.04 to 0.2 A or less than about 0.1 A (based on 300 mm wafer box). In various cases, the current used to etch the material is negative. Current density for the electroplating may be from about 0.1 to ² mA / cm 2. The current density during etching may be about 0.05 to 0.3 mA / cm < ^{2 &} gt ;. In embodiments using a modulated waveform (e.g., a square waveform), the frequency of the waveform may be about 100 to 1000 Hz. In other words, the waveform may alternate between the deposition current and the etching current at this disclosed frequency. The effect of different waveforms on the plating results is further discussed below in the experimental part.

It is believed that the use of a modulated waveform, without being bound by any particular theory or mechanism of action, may result in redistribution of material within and within the feature. During the etched portion of the corrugations, the copper may be selectively etched near the top portion of the feature. Copper that is further down in the feature, i.e., near the bottom of the feature, is less likely to be etched. This elective etching may selectively reduce the surface area of copper in the (and preferably) available features for plating. During the subsequent deposition portion of the waveform, the copper tends to be more deposited toward the bottom of the feature, where the remaining copper is concentrated, which causes the energy required for deposition in this region to reach the top of the feature And may be lower in the nearby regions. While both the deposition and etching operations act on all parts of the feature, the deposition occurs more strongly near the bottom of the feature than at the top, and the etching may occur more strongly near the top of the feature than at the bottom of the feature. Through repetition of deposition and etch cycles, copper may be redistributed within the features to achieve bottom-up filling. Another factor that may contribute to the bottom-up filling mechanism is the relatively low deposition rate. Since plating occurs over a long period of time, copper has a lot of time to redistribute in the features to provide good fill results.

In the case where a DC waveform is used, the action mechanism for promoting the bottom-up filling may be slightly different. When the copper is combined with a complexing agent such as relatively weak complexing agents such as NTA and / or glutamic acid, for example, and plated at a low deposition rate, the filling mechanism becomes less conformal thereby causing the bottom-up It may lead to filling. Selection of complexing agent, copper concentration in electrolyte, electrolyte pH and electrolyte temperature both affect solution polarization. When the substrate was maintained at a potential of about 0.03 to 0.33 V relative to the NHE reference electrode, bottom-up filling appeared to occur reliably. This voltage range appeared to be successful in promoting bottom-up filling. If the voltage is below this range, the plating current will be too low and very little copper will be deposited; If the voltage is higher than this range, the conformal filling behavior is observed rather than the bottom-up filling. By applying a current corresponding to the voltage within the above range, a bottom-up charge can be achieved. In certain embodiments, the voltage is about -0.3 to -0.6 V (e.g., about -0.4 to -0.5 V) for a mercury sulfate reference electrode (MSE), as used in the experiments described below. . By maintaining the voltage within this range, with the electrolyte conditions described above, bottom-up filling is achieved, without the use of organic additives such as inhibitors, accelerators or leveling agents. In some instances, the electrolyte contains trace amounts of organic additives, but these additives do not substantially contribute to the bottom-up filling mechanism.

Figure 1 is a flow chart of a method of electroplating copper into a feature on a substrate having an exposed precious metal layer. Process 100 begins at block 101 where a substrate having an exposed precious metal layer is received / provided into an electrical deposition chamber. The substrate will typically have features on it, and the features will be filled through an electrical deposition process. In some instances, the features may be trenches having a width of about 10 to 100 nm, e.g., about 50 to 100 nm. In these or other embodiments, the features may have a width of about 100 nm or less, e.g., about 20 nm or less. Then, at block 103, the substrate is contacted with an electrolyte substantially free of inhibitors, accelerators or planarizing agents. The electrolyte may have the above-mentioned properties such as complexing agent, low copper cation concentration, and specific pH and / or temperature. These factors may contribute to the relatively strongly polarized electrolyte. At block 105, a current is applied to the substrate. The applied current may be a direct current or modulated current and is designed to maintain a substrate potential of about 0.03 to 0.33 V for the NHE reference electrode. This substrate potential, along with the disclosed electrolyte, facilitates bottom-up filling without the use of organic plating additives.

Plating on the copper seed layer

The above-described method relating to electrodeposition of copper on a semiprecious metal layer may be extended by plating on the copper seed layer. Although this embodiment can not achieve the advantage of a one-step fill (because the copper seed layer is deposited separately from the copper material fill), this embodiment can be used without the use of organic plating additives Takes advantage of electroplating copper through bottom-up filling.

In general, the above teachings relating to electrolyte composition / pH / temperature / waveform also apply to plating on the copper seed layer. However, some of the above considerations are less important when plating on the copper seed layer, and other considerations may be more important. For example, when plating occurs on the copper seed layer, the complexing agent may be omitted from the electrolyte. The complexing agent may be more important than the plating situation on the semiprecious metal layer, since the degree of polarization required to achieve suitable plating results may be higher when plating on the semiprecious metal layer than when plating on the copper have.

Also, when plating on the copper seed layer, the use of modulated waveforms is somewhat more complicated. As in plating on the semiprecious metal layer, the applied current may be galvanostatic or galvano-dynamic. In some areas on the substrate, complexity is added since all copper (including the copper seed layer) may be dissolved during the etched portions of the modulated waveform. If such a bar occurs, there will be no suitable surface for electroplating in this area and the plating results will be poor. Although bottom-up filling can be accomplished using the method described with the modulated waveform, measures must be taken to avoid seed dissolution. Thus, the etched portion of the corrugations may be delayed until a sufficient copper amount is plated in the initial portion of the plating sequence. In addition, plating on the copper seed layer may also be achieved using a DC waveform.

The optimal deposition temperature may be lower than in the embodiment employing the copper seed layer as compared to the embodiment in which plating occurs directly on the precious metal layer. In some cases, when plating on the copper seed layer, the temperature is maintained at about 20 to 80 캜, such as about 20 to 50 캜.

Without being bound to any mechanism of action, the mechanism for bottom-up filling on the copper seed layer may be similar to the bottom-up filling mechanism described above in connection with plating on a precious metal layer such as ruthenium. However, in various cases, when plating on the copper seed layer, it is not necessary to use a modulated waveform to facilitate nucleation on the complexing agent or copper seed layer.

2 is a flow chart of a method of electroplating copper into a feature on a substrate having an exposed copper seed layer. Process 200 begins at block 201 where a substrate having an exposed copper seed layer is received / provided into an electrical deposition chamber. The substrate will typically have features on it, and the features will be filled through an electrical deposition process. In some instances, the features may be trenches having a width of about 10 to 100 nm, e.g., about 50 to 100 nm. Then, at block 203, the substrate is contacted with an electrolyte substantially free of inhibitors, accelerators or planarizing agents. The electrolyte may have the above-mentioned properties such as complexing agent, low copper cation concentration, and specific pH and / or temperature. In certain embodiments employing a copper seed layer, a complexing agent is not used. At block 205, a current is applied to the substrate. The applied current may be a direct current or modulated current and is designed to maintain a substrate potential of about 0.03 to 0.33 V for the NHE reference electrode. This substrate potential, along with the disclosed electrolyte, facilitates bottom-up filling without the use of organic plating additives.

Device

Multiple device configurations may be used in accordance with the embodiments disclosed herein. One exemplary apparatus includes a clamshell fixture that seals the backside of the wafer from the plating solution while the plating proceeds with respect to the plane of the wafer. The clam shell fixture may support the wafer by, for example, supporting a wafer through a seal disposed over the bevel of the wafer or by a vacuum applied to the backside of the wafer with a seal used near the bevel.

The clam shell fixture must enter the bath in a manner that allows for good wetting of the plating surface of the wafer. Substrate wetting quality is not limited, but is influenced by a number of variables including the clam shell rotational speed, the vertical entrainment rate, and the angle of the clam shell relative to the surface of the plating bath. These variables and their effects are further discussed in U.S. Patent No. 6,551,487, which is incorporated herein by reference. In certain embodiments, the electrode rotation rate is about 5 to 125 RPM, the vertical entry speed is about 5 to 300 mm / s, and the angle of the clamshell to the surface of the plating bath is about 1 to 10 degrees. One of the purposes of optimizing these variables for a particular application is to achieve a good wetting by removing as much air from the wafer surface as possible.

The electrodeposition methods disclosed herein are described with reference to various electroplating tool devices and may be employed in the context of these electroplating tool devices. One example of a plating apparatus that may be used in accordance with embodiments herein is the Lam Research Saber tool. Electrical deposition, including substrate immersion and other methods disclosed herein, may be performed in components that form a large electrical deposition apparatus. Figure 3 shows a schematic top view of an exemplary electrical deposition apparatus. The electrodeposition device 900 may include three individual electroplating modules 902, 904, 906. The electrical deposition apparatus 900 may further include three separate modules 912, 914 and 916 configured for various process operations. For example, in some embodiments, one or more of modules 912, 914, and 916 may be a spin rinse drying (SRD) module. In other embodiments, one or more of the modules 912, 914, and 916 may be a post-electrofilm module (PEM), and each module may be configured to process substrates by one of the electroplating modules 902, 904, and 906 The substrate may be configured to perform functions such as edge bevel removal, backside etching, and acid cleaning on the substrates.

The electrical deposition apparatus 900 includes a central electrical deposition chamber 924. This central electrical deposition chamber 924 is a chamber that holds the chemical solution used as the electroplating solution in the electroplating modules 902, 904, and 906. The electrical deposition apparatus 900 further includes a dosing system 926 that may store and deliver electrolyte components for the electroplating solution. The chemical dilution module 922 may store and mix the compatibilizers to be used as an etchant. The filtration and pumping portion 928 may filter the electroplating solution for the central electrical deposition chamber 924 and pump it to the electroplating modules.

The system controller 930 provides the electronic and interface controls required to operate the electrical deposition apparatus 900. A system controller 930 (which may include one or more physical controllers or logical controllers) controls some or all of the characteristics of the electroplating apparatus 900. In some embodiments, the system controller 930 typically includes one or more memory devices and one or more processors. The processor includes a CPU, a computer, analog and / or digital input / output connections, a stepper motor controller board, and other similar components. Instructions for implementing appropriate control operations may be executed on the processor. These instructions may be stored on a memory device associated with the system controller 930 or provided on a network. In certain embodiments, system controller 930 executes system control software.

The system control software in the electronic digestion device 900 can be used to control the timing of certain processes performed by the electrical digestion device 900, mixing of electrolyte components (including the concentration of one or more electrolyte components), inlet pressure, , Plating cell temperature, substrate temperature, current and potential applied to the substrate and any other electrodes, substrate position, substrate rotation, and other parameters. The system control logic may further include instructions for electroplating under conditions where the lower copper concentration electrolyte and its associated relatively high overpotential are fitted. For example, the system control logic may be configured to provide a relatively low current density during bottom-up filling. The control logic may also be configured to provide certain levels of mass transfer to the wafer surface during plating. For example, the control logic may be configured to control the flow of electrolyte to ensure sufficient mass transfer to the wafer during plating so that the substrate does not encounter depleted copper conditions. In certain embodiments, the control logic may be operative to provide different levels of mass transfer in different stages of the plating process (e. G., Higher during the bottom-up charge stage than during the overburden stage) Lower mass delivery during bottom-up filling stages than during mass transfer or excess layer stages). In addition, the system control logic may be configured to maintain the pH of the electrolyte or the concentration of one or more electrolyte components within any of the ranges disclosed herein. In certain instances, the system control logic may be configured to maintain the concentration of copper cations between about 1 and 100 mM. In another example, the system control logic may be configured to apply current to maintain the substrate at a potential of about 0.03 to 0.33 V relative to the NHE electrode. The system control logic may be configured in any suitable manner. For example, various process tool component sub-routines or control objects may be described to control the operation of the process tool components required to execute the various process tool processes. The system control software may be coded in any suitable computer readable programming language. The control logic may also be implemented as hardware in a programmable logic device (e.g., an FPGA), an ASIC, or other suitable means.

In some embodiments, the system control logic includes an input / output control (IOC) that sequences instructions for controlling various parameters as described above. For example, each phase of the electroplating process may include one or more instructions to be executed by the system controller 930. Instructions for setting process conditions for the immersion process phase may be included in the corresponding immersion recipe phase. In some embodiments, the electroplating recipe phases may be configured sequentially so that all instructions for the electroplating process phase are performed simultaneously with this process phase.

The control logic may be divided into various components such as programs or sections of programs in some embodiments. Examples of each of these components for this purpose include a substrate positioning component, an electrolyte composition control component, a pressure control component, a heater control component, and a potential / current power control component.

In some embodiments, there may be a user interface associated with the system controller 930. The user interface may include a user input device such as a display screen, a graphical software display in device and / or process state, a pointing device, a keyboard, a touch screen, a microphone,

In some embodiments, parameters that are controlled by the system controller 930 may be related to process conditions. Non-limiting examples include bath conditions (temperature, composition, pH, flow rate, etc.), substrate position (rotation rate, linear velocity, angle from horizontal, etc.) and electrical conditions (current, Potential, etc.). These parameters may be provided to the user in the form of a recipe, which may be entered using a user interface.

Signals for monitoring the process may be provided by the analog and / or digital input connections of the system controller 930 from various process tool sensors. A signal for controlling the process may be output on the analog output connection and the digital output connection of the process tool. Non-limiting examples of such process tool sensors may include a mass flow controller, a pressure sensor (such as a manometer), a thermocouple, an optical position sensor, and the like. A suitably programmed feedback and control algorithm can be used with the data from these sensors to maintain process conditions.

In one embodiment, the instructions can include instructions for inserting a substrate into a wafer holder, tilting the substrate, biasing the substrate during immersion, and electrically depositing a copper-containing structure on the substrate.

The hand-off tool 940 selects a substrate from a substrate cassette, such as cassette 942 or cassette 944. The cassette 942 or the cassette 944 may be a front opening unified pod (FOUP). The FOUP is an enclosure designed to keep the substrate safe and stable in a controlled environment and allow the substrate to be moved apart for processing or measurement by tools equipped with suitable loading ports and robotic handling systems. The hand-off tool 940 can hold the substrate using vacuum adsorption or some other adsorption mechanism.

The handoff tool 940 may interface with the wafer handling station 932, the cassette 942 or 944, the transfer station 950, or the aligner 948. From the transfer station 950, the handoff tool 946 may obtain access to the substrate. The transfer station 950 may be a position or slot where the handoff tool 940, 946 does not pass through the aligner 948 and conveys or receives the substrate therefrom. However, in some embodiments, the handoff tool 946 aligns the substrate with the aligner 948 so that the substrate is properly aligned on the handoff tool 946 for accurate delivery to the electroplating module. . The handoff tool 946 may also transfer the substrate to one of the electroplating modules 902, 904, 906 or to separate modules 912, 914, and 916 configured for various process operations.

An example of a process operation according to the above-described methods may proceed as follows: (1) electrodeposition copper onto a substrate to form a copper-containing structure within the electroplating module 904; (2) rinse and dry the substrate with SRD in module 912; (3) Edge bevel removal is performed in module 914.

Devices configured to efficiently circulate substrates across sequential plating operations, rinsing operations, drying operations, and PEM process operations may be used to implement them for use in a manufacturing environment. To achieve this, the module 912 may be configured as a spin-rinse dryer and an edge bevel removal chamber. With such a module 912, the substrate only needs to be transferred between the electroplating module 904 and the module 912 for copper plating operations and EBR operation.

Another embodiment of the electrical deposition apparatus 1000 is schematically illustrated in FIG. In this embodiment, the electrical deposition apparatus 1000 comprises a set of a plurality of electroplating cells 1007, each electroplating cell comprising an electroplating bath, the set having a pair configuration Or have multiple duet configurations. In addition to the electroplating operation itself, the electrical deposition apparatus 1000 may be fabricated by any suitable process, including, for example, spin-rinsing, spin drying, metal and silicon wet etching, electroless deposition, electropolishing, pre- Processes and sub-steps associated with various other electroplating processes such as treatment, reduction, annealing, photoresist stripping, and the like. The electrical deposition apparatus 1000 is shown in a top-down schematic top view in FIG. 4 and only one level or "floor" is shown in this figure, but devices such as the Lam Research Saber ^TM 3D tool Those skilled in the art will readily appreciate that these can potentially have two or more levels stacked one above the other, with processing stations of the same or different type.

Referring again to FIG. 4, the substrate 1006 to be electroplated is generally supplied to the electrical deposition apparatus 1000 through the front-end loading FOUP 1001 and from the FOUP to the front-end robot 1002 in this example To the main substrate processing zone of the electrical deposition apparatus 1000 which is driven by the spindle 1003 in multiple dimensions in one station to another station of the accessible stations The substrate 1006 can be retracted and moved, and in this example, two front-end accessible stations 1004 and also two front-end accessible stations 1008 are shown. The front-end accessible stations 1004 and 1008 may include, for example, preprocessing stations and spin-rinse drying (SRD) stations. The lateral movement of the front end robot 1002 can be achieved using the robot track 1002a. Each of the substrates 1006 is held by a cup / cone assembly (not shown) driven by a spindle 1003 connected to a motor (not shown), and the motor can be attached to the mounting bracket 1009. Also, in this example, it is shown to be composed of four pairs of dip or electroplating cell sets 1007 for a total of eight electroplating cells 1007. Electroplating cells 1007 can be used for electroplating copper and solder materials for solder structures for copper containing structures. A system controller (not shown) may be coupled to the electrical deposition apparatus 1000 to control all or some of the characteristics of the electrical deposition apparatus 1000. The system controller may be programmed or otherwise configured to execute instructions in accordance with the processes described herein earlier.

The film lithography patterning typically includes some or all of the following steps, each of which is realized using a number of possible tools, which steps include (1) using a spin on or spray on tool to form a silicon nitride (2) curing the photoresist using a hot plate or a furnace or other suitable curing tool, (3) curing the photoresist using a tool such as a wafer stepper, Exposing the resist to visible or ultraviolet or x-ray light, (4) developing the photoresist to selectively remove and pattern the resist using a tool such as a wet bench or spray developer, (5) Using a dry or plasma-assisted etch tool, Transferring the resist pattern to the top piece, and (6) removing the photoresist using a tool such as a RF or microwave plasma resist stripper. In some embodiments, an ashable hard mask layer (e.g., an amorphous carbon layer) and another suitable hard mask (e.g., an anti-reflective layer) may be deposited prior to applying the photoresist.

It is to be understood that the specific embodiments or examples described herein are illustrative in nature and that many variations are possible, so that these specific embodiments or examples should not be construed as limiting. The particular routine or method described herein may represent one or more any number of processing strategies. As such, the various operations illustrated may be performed in parallel, in other sequences, or in some instances, in the order shown. Likewise, the order of the processes described above may vary.

The subject matter of this disclosure is intended to cover any and all embodiments of the novel and non-claimed subject matter of the various processes, systems and configurations disclosed herein, other features, functions, operations, and / One combination and subcombinations.

Experiment

Several experimental studies have shown that the disclosed methods can be used to achieve bottom-up filling even in the absence of organic plating additives. The initial results provided in this section are for cyclic voltammetry (CV) scans that show the effect of different parameters (e.g., stagnation of complexing agent, copper cation concentration, solution pH and solution temperature) on polarization. The latter results provided in this section represent filling results for filled features according to different plating conditions. All the results provided in this section were generated without the use of organic plating additives. When coupons are used for plating, the coupons have a plating area of about 1 cm ² .

Figure 5 shows the CV results illustrating the relative effects of different complexing agents on the polarization of the electrolyte. The tested electrolyte contained 5 mM copper cations and 5 mM related complexing agents. CVs were collected for a platinum rotating disk electrode (RDE) in a beaker with a MSE (mercury sulfite reference electrode) at a rotation rate of 200 RPM and a scan rate of 10 mV / s. The dissolved oxygen was controlled to be about 1 ppm and the pH was adjusted to about 3 by TMAH (tetramethylammonium hydroxide) or sulfuric acid. EDTA (ethylenediaminetetraacetic acid) solution was most strongly polarized, and sulfite (SO ₄ ) solution was minimally polarized. The sulfite solution was minimally polarized in this case because the copper only formed complexes with water.

Figure 6 shows CV results illustrating the relative effects of different copper ion concentrations and pH levels on polarization of a solution containing EDTA as a complexing agent. In each of these solutions, the copper cation concentration and EDTA concentration were equimolar. The results were collected for a platinum rotating disk electrode (RDE) in a beaker at a rotation rate of 200 RPM and a scan rate of 10 mV / s, while the pH was adjusted to the level specified by TMAH or sulfuric acid. The reference electrode is an MSE electrode. Low copper concentrations and high pH levels result in more polarized solutions.

Figure 7 shows CV results illustrating the effect of electrolyte temperature on polarization of solutions containing 10 mM copper cations and 10 mM EDTA. Data were collected for PVD copper seed coupons attached on RDE electrodes at different temperatures, with a rotational speed of 200 RPM and a scan rate of 10 mV / s. In this case the reference electrode was MSE, the level of dissolved oxygen was about 1 ppm, and the pH was adjusted to about 2.3 by TMAH or sulfuric acid. Scanning results show that cold temperatures result in more strongly polarized solutions.

Figures 8a-8c show SEM (Raman spectra) showing the resultant filling for ruthenium seeded trench coupons attached to RDE electrodes after plating in an electrolyte containing 10 mM copper cations and 10 mM EDTA. scanning electron microscope images. The pH of each electrolyte was adjusted to about 2.3 pH by TMAH or sulfuric acid. The dissolved oxygen level of each electrolyte was about 1 ppm. The temperature of each electrolyte was about 70 캜. In this case, the trenches have a width of about 80 nm, but these techniques may also be applied to narrower width trenches (e.g., trenches of about 20 nm width). The rotation speed of the RDE was about 200 RPM and the reference electrode was the MSE electrode. Each of the coupons shown in Figures 8A-8C was plated under galvanostatic conditions. The coupon shown in Fig. 8A was plated at 0.4 mA, the coupon shown in Fig. 8B was plated at 0.6 mA, and the coupon shown in Fig. 8C was plated at 1 mA.

A void-free bottom-up filling was achieved within 80 nm trenches for coupons plated at 0.4 mA and 0.6 mA. However, when the DC current increased to 1 mA, seams were observed as indicated by the white arrows in Fig. 8C. Filling quality was also checked after the annealing operation and voids were not observed in coupons plated at 0.4 mA and 0.6 mA (i.e., the coupons shown in FIGS. 8A and 8B). Experiments performed under a wide range of conditions are achieved when the voltage applied to the non-pore bottom-up fill is maintained at about -0.3 to -0.6 V (e.g., -0.4 to -0.5 V) relative to the MSE reference electrode . Since the MSE electrodes are not standardized and can produce different potential readings depending on the specific filling of the electrode, the results are also reported in terms of potential for a standard NHE electrode. Compared with NHE electrodes, this may be achieved when the non-porous bottom-up charge is maintained in the range of about 0.03 to 0.33 V. At voltages outside this range, shims were observed.

Figures 9a-9c show SEM images of ruthenium seeded trench coupons attached to the RDE and plated using waveforms modulated at different temperatures, currents, and plating times. Each of the electrolytes used for plating in FIGS. 9A-9C had 10 mM copper cations and 10 mM EDTA, the pH was adjusted to about 2.3 pH by TMAH or sulfuric acid, and had a dissolved oxygen content of about 1 ppm. In each case, the rotation speed was about 200 RPM and the reference electrode was the MSE electrode. In each case, the modulated waveform was a square wave alternating between the deposition current and the etching current at a frequency of about 100 Hz (about 50 to 1000 Hz frequency was tested and showed good fill results). At each deposition, the etching current was set at -0.05 mA and the voltage was maintained at about -0.4 to -0.5 V for the MSE electrode.

The coupon shown in FIG. 9A was electroplated at room temperature for 20 minutes, using a deposition current level of 0.45 mA. The coupon shown in FIG. 9B was electroplated at 50 DEG C for 20 minutes, using a deposition current level of 0.5 mA. The coupon shown in Figure 9c was electroplated at 70 占 폚 for 8 minutes, using a deposition current level of 1.4 mA. In each of the cases shown in Figs. 9A-9C, non-pore bottom-up filling was achieved, but filling occurred more rapidly at higher temperatures. Actually, the filling rate at 70 캜 was about 10 times higher than the filling rate at room temperature.

Figures 10A and 10B show SEM images of ruthenium seeded trench coupons attached to RDE and plated in electrolytes having different complexing agents. The coupons shown in Figure 10a were plated in an electrolyte having a 5 mM copper cation and 5 mM NTA, pH adjusted to about 3.1 pH by TMAH or sulfuric acid and having a dissolved oxygen content of about 1 ppm. The coupons shown in Figure 10b were plated in an electrolyte having a 10 mM copper cation and 10 mM glutamic acid, the pH being adjusted to about 3.1 pH and having a dissolved oxygen content of about 1 ppm. In each case, the rotational speed was about 200 RPM, the temperature was room temperature, the reference electrode was the MSE electrode, and the waveform used to drive the deposition was galvanostatic (0.1 mA for FIG. 10A / NTA and FIG. 10B / 0.6 mA). A good quality bottom-up filling was achieved in both cases.

In another experiment, bottom-up filling was achieved for a plated ruthenium seeded coupon in an electrolyte that does not have a complexing agent. In this case, the electrolyte comprised a 10 mM CuSO ₄ at pH 2.3. Modulated waveforms were used to plate copper, and the modulated waveforms are similar to those used in connection with Figs. 9A-9C.

The remainder of the experiments involve plating on coupons with a copper seed layer. Figs. 11a-c are cross-sectional SEM images of copper-seeded coupons filled at different temperatures, and Figs. 12a-12c show top-down SEM images of these same coupons (after chemical mechanical polishing) Respectively. Copper-seeded coupons were attached to RDE, had 10 mM copper cations and 10 mM EDTA and the pH was adjusted to about 2.3 pH by TMAH or sulfuric acid, and at an electrolyte having a dissolved oxygen content of about 1 ppm, And plated using an MSE electrode as the electrode. The plated coupons in Figures 11a-c and 12a-12c show a potentiostatic entry triggered 0.25 s into the electrolyte at -0.5 V open circuit potential and a potentiostatic entry at a later 0.2 mA current Plated through a process having a nysteretic deposition. The trenches in the coupons had a width of about 50 nm. The coupons shown in Figs. 11A and 12A were plated at room temperature, the coupons shown in Figs. 11B and 12B were plated at 50 DEG C, and the coupons shown in Figs. 11C and 12C were plated at 70 DEG C. Good quality non-air-borne bottom-up filling was achieved at room temperature. However, at temperatures above 70 ° C, seed dissolution and growth deficiencies appear to occur at a relatively low current density (0.2 mA) selected for this particular test. As such, the benefits of higher plating rates at high temperatures must be balanced with the increased likelihood of seed dissolution at such high temperatures.

Figure 13 shows a transmission electron microscope image of a copper-seeded trench coupon plated in an electrolyte without complexing agent. In this case, the electrolyte contained 10 mM copper cations, about 1 ppm dissolved oxygen, and pH 2.3. The rotation speed was 200 RPM and the reference electrode was the MSE electrode. A 0.25 second triggered potentiostatic entry into the electrolyte at -0.5 V to the open circuit potential was used followed by a galvanostatic plating at 1.2 mA current. As illustrated in Figure 13, a good quality bottom-up filling has been achieved. Thus, in some embodiments, the complexing agent may be omitted from the electrolyte.

Claims (32)

CLAIMS What is claimed is: 1. A method of performing a single step electrofill process to fill features on a partially fabricated integrated circuit,
(a) receiving the substrate having a semi-noble metal layer and a plurality of features exposed on the substrate;
(b) contacting the substrate with an electrolyte,
The electrolyte,
(i) about 1 to 100 mM copper cations; And
(ii) a complexing agent that forms a complex with the copper cations,
Contacting the substrate with an electrolyte wherein the electrolyte is substantially free of inhibitors, accelerators, and a planarizing agent; And
(c) a bottom-up filling mechanism at a substrate potential for electrodeposition of about 0.03 to 0.33 V relative to an NHE (normal hydrogen eletrode) reference electrode while being in contact with the electrolyte, And electroplating the copper into the features.
A method for performing a single stage electric charge process. The method according to claim 1,
The inhibitor, accelerator or leveling agent may be selected from the group consisting of:
A method for performing a single stage electric charge process. The method according to claim 1,
Wherein the bottom-up filling is performed directly on the semi-precious metal layer without first forming a seed layer,
A method for performing a single stage electric charge process. The method according to claim 1,
The electroplating of copper in (c) comprises alternating currents to a first level for depositing copper on the substrate and a second level for etching copper from the previously electroplated copper on the substrate, The method comprising the steps of:
A method for performing a single stage electric charge process. 5. The method of claim 4,
The second level of current for etching copper has an absolute value of about 0.05 to 0.3 mA / cm < ² >
Pulses of current alternate between a first current level and a second current level at a frequency of about 100 to 1000 Hz,
A method for performing a single stage electric charge process. 6. The method according to any one of claims 1 to 5,
Wherein the complexing agent is selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), citric acid, and glutamic acid.
A method for performing a single stage electric charge process. The method according to claim 6,
The complexing agent may be ethylenediaminetetraacetic acid (EDTA)
A method for performing a single stage electric charge process. The method according to any one of claims 1 to 5,
During electroplating, the electrolyte is maintained at a temperature of about < RTI ID = 0.0 > 20-80 C,
A method for performing a single stage electric charge process. 9. The method of claim 8,
During electroplating, the electrolyte is maintained at a temperature of about 50-70 < 0 > C,
A method for performing a single stage electric charge process. 6. The method according to any one of claims 1 to 5,
During electroplating, the electroplating surface of the substrate that experienced the range of about 0.1 to ² mA / cm 2 current density,
A method for performing a single stage electric charge process. 6. The method according to any one of claims 1 to 5,
Wherein the electrolyte has a pH of about 1 to 5,
A method for performing a single stage electric charge process. 6. The method according to any one of claims 1 to 5,
Wherein the semi-precious metal layer comprises a material selected from the group consisting of ruthenium, tungsten, cobalt, osmium, platinum, palladium, aluminum, gold, silver, iridium,
A method for performing a single stage electric charge process. 13. The method of claim 12,
Wherein the semi-precious metal layer comprises ruthenium,
A method for performing a single stage electric charge process. 6. The method according to any one of claims 1 to 5,
Wherein at least a portion of the features have a width less than about 100 nm,
A method for performing a single stage electric charge process. 15. The method of claim 14,
Wherein at least a portion of the features have a width of about 20 nm or less,
A method for performing a single stage electric charge process. 6. The method according to any one of claims 1 to 5,
Wherein the electrolyte comprises less than about 2 ppm dissolved oxygen,
A method for performing a single stage electric charge process. CLAIMS What is claimed is: 1. A method of performing a single step electrofill process to fill features on a partially fabricated integrated circuit,
(a) receiving the substrate having a semi-noble metal layer and a plurality of features exposed on the substrate;
(b) contacting the substrate with an electrolyte, wherein the electrolyte comprises about 1 to 100 mM copper cations, wherein the electrolyte is substantially free of inhibitors, accelerators, and a planarizing agent; Contacting; And
(c) alternately pulsing current to a first level for depositing copper on the substrate while contacting the substrate with the electrolyte and a second level for etching copper from the previously electroplated copper on the substrate By applying a modulated waveform, a bottom-up filling mechanism at substrate potential for electrodeposition of about 0.03 to 0.33 V for a normal hydrogen eletrode reference electrode, ≪ RTI ID = 0.0 > electroplating < / RTI >
A method for performing a single stage electric charge process. 18. The method of claim 17,
The second level of current for etching copper has an absolute value of about 0.05 to 0.3 mA / cm < ² >
Pulses of current alternating between about 100 and 1000 Hz between a first current level and a second current level,
A method for performing a single stage electric charge process. CLAIMS 1. A method of depositing copper in a feature on a partially fabricated integrated circuit,
(a) receiving the substrate having a plurality of features and a copper seed layer on a substrate;
(b) contacting the substrate with an electrolyte, wherein the electrolyte comprises about 1 to 100 mM copper cations, wherein the electrolyte is substantially free of inhibitors, accelerators, and a planarizing agent; Contacting; And
(c) electroplating copper into the feature by a bottom-up filling mechanism at a potential of about 0.03 to 0.33 V relative to an NHE (normal hydrogen eletrode) reference electrode.
Copper deposition method. 20. The method of claim 19,
During electroplating, the electrolyte is maintained at a temperature of about < RTI ID = 0.0 > 20-80 C,
Copper deposition method. 21. The method of claim 20,
During electroplating, the electrolyte is maintained at a temperature of about 20-50 < 0 > C,
Copper deposition method. 20. The method of claim 19,
During electroplating, the electroplating surface of the substrate with a range of about 0.1 to ² mA / cm 2 current density,
Copper deposition method. 23. The method according to any one of claims 19 to 22,
Wherein the electrolyte has a pH of about 1 to 5,
Copper deposition method. 23. The method according to any one of claims 19 to 22,
Wherein at least a portion of the features have a width less than about 100 nm,
Copper deposition method. 25. The method of claim 24,
Wherein at least a portion of the features have a width of about 20 nm or less,
Copper deposition method. 23. The method according to any one of claims 19 to 22,
The step of electroplating copper in (c) comprises applying a galvanostatically controlled current to the substrate.
Copper deposition method. An apparatus for electroplating copper into features on a substrate,
(a) one or more electroplating baths configured to receive an electrolyte;
(b) a substrate support; And
(c) a controller having an instruction set,
The instruction set includes:
Receiving the electrolyte into the one or more electroplating baths;
Immersing the substrate in the electrolyte;
Up charge mechanism that is substantially independent of the presence of inhibitors, accelerators or planarizing agents by maintaining a substrate potential of about 0.03 to 0.33 V for an NHE (normal hydrogen eletrode) reference electrode, For electroplating the substrate,
Copper electroplating equipment. 28. The method of claim 27,
Wherein the controller further comprises instructions for applying a modulated waveform that alternately pulses a current to a first current level that deposits copper on the substrate and a second current level that etches copper from the substrate.
Copper electroplating equipment. 28. The method of claim 27,
The second current level for etching the copper has a size of about 0.05 to 0.3 mA / cm < ² >
Wherein pulses of current alternate at a frequency of about 100 to 1000 Hz between the first current level and the second current level,
Copper electroplating equipment. 28. The method of claim 27,
Wherein the controller further comprises instructions for maintaining the electrolyte at a temperature of about 20 to < RTI ID = 0.0 > 80 C <
Copper electroplating equipment. 31. The method of claim 30,
Wherein the controller comprises instructions for maintaining the electrolyte at a temperature of about 50 to < RTI ID = 0.0 > 70 C <
Copper electroplating equipment. 32. The method according to any one of claims 27 to 31,
The controller, further comprising instructions for controlling the electroplating the surface of the substrate so as to experience a range of about 0.1 to ² mA / cm 2 current density,
Copper electroplating equipment.

Images